1. Technical Field
The present disclosure is directed to digital control of loudspeakers and particularly to nonlinear digital control systems for implementation in audio signal processing.
2. Background
Mobile technologies and consumer electronic devices (CED) continue to expand in use and scope throughout the world. In parallel with continued proliferation, there is rapid technical advance of device hardware and components, leading to increased computing capability and incorporation of new peripherals onboard a device along with reductions in device size, power consumption, etc. Most devices, such as mobile phones, tablets, and laptops, include audio communication systems and particularly one or more loudspeakers to interact with and/or stream audio data to a user.
Every device has an acoustic signature, meaning the audible characteristics of a device dictated by its makeup and design that influence the sound generated by the device or the way it interacts with sound. The acoustic signature may include a range of nonlinear aspects, which potentially depend on the design of the device, on the age of the device, the content of an associated stream (e.g. sound pressure level, spectrum, etc.), and/or the environment in which the device operates. The acoustic signature of the device may significantly influence the audio experience of a user.
Audio experience is one of many factors considered in the design of consumer electronic devices. Often, the quality of audio systems, loudspeakers, etc. are compromised in favor of other design factors such as cost, visual appeal, form factor, screen real-estate, case material selection, hardware layout, and assembly considerations amongst others.
Many of these competing factors are favored at the expense of the audio quality, as determined by the audio drivers, component layout, loudspeakers, material and assembly considerations, housing design, etc. In addition, due to the reduced available real estate and miniaturized component size, nonlinearities in the acoustic characteristics of such devices are becoming particularly relevant as the loudspeakers in such devices are being pushed to the limits of their capabilities.
Improved acoustic performance may be achieved, generally with additional cost, increased computational complexity, and/or increased component size. Such aspects are in conflict with the current design trend. As such, cost, computation, and size sensitive approaches to addressing nonlinear acoustic signatures of devices would be a welcome addition to a designer's toolbox.